The present invention relates generally to a process of fabricating inflatable soft vinyl products having irregular contours and extremities. In particular, the present invention is applicable to the fabrication of a life-like inflatable doll that resembles a human figure, and that includes realistic three-dimensional anatomical features of an actual human figure.
There are many inflatable polyvinyl chloride (PVC) products available on the market today. Generally, these products assume a substantially flat, two-dimensional shape when deflated, and a three-dimensional shape when inflated. The inflated product is often one that provides buoyancy in the water, and has a nondescript geometric shape. However, novelty inflatable products that assume a recognizable shape when inflated are also available. Some of these novelty products are animal-shaped, and are sold as toys for children. Others are shaped like mannequins, either for use in displaying items of clothing, or for sale as an adult novelty.
Conventionally, these products are formed of flat sheets of PVC or other flexible polymer, joined at seams to form an airtight enclosure having a valve for inflating and deflating the product with air or any other appropriate fluid. For example, two flat sheets of PVC, usually in the range of 0.18 mm to 0.35 mm in thickness (7 to 14 gauge), are cut to the size required for the particular application. As shown in FIG. 1, these sheets 4 are placed under a conventional horizontally-mounted high frequency (HF) welding machine 2, one sheet over the other. A cutting die in the required shape is placed over the top sheet and the welding machine descends and welds the two pieces of PVC sheet together along a seam in the shape of the die.
For example, in the case of an inflatable human mannequin, the cutting die may be in the shape of a torso or hand. According to the conventional method, the resulting PVC torso or hand is a two-dimensional form made from the two flat PVC sheets, and will only acquire a three-dimensional appearance when inflated; the two sheets lie flat when not inflated. For a female mannequin, a pair of hollow breast pieces are also usually made from PVC, either molded in an injection molding process or a slush/rotational molding process, or formed as a simple structure by joining several pieces of PVC sheet into cone shapes to resemble breasts. FIGS. 2-7 show a typical process. The breast pieces 6 are hollow, and have concave interiors 8. The breast pieces 6 are put into place on the previously-formed torso piece 10. The breast pieces 6 are then welded onto the torso portion 10 at the peripheries, also by using a conventional vertically-mounted HF welding machine 12. As shown in FIG. 6, a distinct joining line or seam 14 is apparent at the rim of the breast pieces 6 where they join the torso portion 10. As a result, the finished mannequin 16 is not a realistic replica of a female human body.
Because the objective is to create an inflatable mannequin that is life-like in appearance, such joining lines and seams at the breast pieces and at other prominent locations are a drawback in that they detract from the realistic qualities of the doll. Generally, such seams are present in all inflatable PVC products formed according to the described conventional fabrication process, and will diminish the aesthetic quality of any inflatable product that is intended to have a smooth surface or that is meant to resemble an existing object or creature.
A further drawback to the conventional process is that contours of the inflated product are limited, because flat sheets of PVC are used to form the different portions of the finished assembly. When the finished product is inflated, these sheets expand and form smooth three-dimensional surfaces. It is not possible, according to the conventional process, to include irregular contours in these smooth surfaces. In the case of a human mannequin, this absence of variation in contour results in a mannequin that is not life-like, because it lacks such features as a collarbone, ribs, and a navel, as well as details of the hands, such as knuckles. Lacking these features, as well as natural body curves and contours present in real people, the mannequin has an unnatural appearance. A realistic appearance is important to owners of such mannequins, and this unnatural appearance is understandably a disappointment to them.
It is therefore an objective of the present invention to provide a process of fabricating an inflatable vinyl product that minimizes the number of visible seams in the finished product.
It is a further objective of the present invention to provide a process of fabricating an inflatable vinyl product that results in a finished product having visible seams in only unimportant areas of the finished product.
It is another objective of the present invention to provide a process of fabricating an inflatable vinyl product that creates contours in the otherwise smooth surfaces of the finished product.
It is an additional objective of the present invention to provide a process of fabricating an inflatable human mannequin that includes natural body contours and protrusions.
It is also an objective of the present invention to provide a welding machine that enables accurate manual alignment of PVC sheets used to form a more realistic human mannequin.
The present invention is a process of fabricating an inflatable item. According to a first aspect of the present invention, the process includes providing first and second three-dimensional molds and placing first and second flexible polymer sheets over respective ones of the first and second molds. The polymer sheets are heated until the sheets conformally coat the respective molds. The heated polymer sheets are cooled such that the sheets retain the three-dimensional shapes of the respective molds. Peripheral edges of the first polymer sheet and the second polymer sheet are welded to each other to form a sealed flexible shell having an interior space that can be filled with fluid to inflate the shell such that the shell forms a three-dimensional shape. The first and second molds, when placed so as to abut each other, preferably form the three-dimensional shape of the shell when the shell is inflated. The flexible polymer sheets may be made of vinyl. Heating the polymer sheets until the sheets conformally coat the respective molds may include spreading the polymer evenly over the surface of the respective mold. In a preferred embodiment, welding peripheral edges of the first polymer sheet and the second polymer sheet to each other includes placing the cooled polymer sheets on respective plates of a high frequency welding machine, and moving the plates toward each other until the peripheral edges of the cooled polymer sheets touch each other. The plates may be disposed in a substantially vertical plane. The plates of the welding machine may be disposed on horizontal shafts, and moving the plates toward each other includes moving the shafts such that the plates move horizontally toward each other. The three-dimensional shape of the shell may be the shape of a human body, and particularly a human female body. Alternatively, the three-dimensional shape of the shell may be the shape of a human torso, and particularly a human female torso. In this case, the first three-dimensional mold includes three-dimensional features of a front of a human female torso, including breasts, a navel, and a collarbone. Further, the second three-dimensional mold includes three-dimensional features of a back of a human female torso, including shoulder blades, a lumbar curve, and buttocks. Preferably, a valve is added to the flexible shell, through which a fluid can be provided to the interior space from outside of the shell in order to inflate the shell.
According to another aspect of the present invention, the process of fabricating an inflatable item includes providing first and second three-dimensional molds, wherein the molds, when placed together, form the shape of a human torso. First and second flexible polymer sheets are placed over respective ones of the first and second molds. The polymer sheets are heated until the polymer of the sheets flows to conformally coat the respective molds. The heated polymer sheets are cooled until the polymer no longer flows, such that the sheets retain the three-dimensional shapes of the respective molds. Peripheral edges of the first polymer sheet and the second polymer sheet are welded to each other to form a sealed flexible shell having an interior space that can be filled with fluid to inflate the shell such that the shell forms a three-dimensional shape of a human torso. Preferably, the sealed flexible shell only has welding seams along side surfaces of the human torso shape. In a preferred embodiment, the human torso shape of the sealed flexible shell includes three-dimensional features including breasts, a navel, a collarbone, shoulder blades, a lumbar curve, and buttocks, which may approximate corresponding features of an actual person. The flexible polymer sheets may be made from PVC. In a preferred embodiment, welding peripheral edges of the first polymer sheet and the second polymer sheet to each other includes placing the cooled polymer sheets on respective plates of a high frequency welding machine, and moving the plates toward each other until the peripheral edges of the cooled polymer sheets touch each other. The plates may be disposed in a substantially vertical plane. The plates of the welding machine may be disposed on horizontal shafts, and wherein moving the plates toward each other includes moving the shafts such that the plates move horizontally toward each other. Preferably, a valve may be added to the flexible shell, through which a fluid can be provided to the interior space from outside of the shell in order to inflate the shell.